in6_cksum.c

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    1 /*-
    2  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 3. Neither the name of the project nor the names of its contributors
   14  *    may be used to endorse or promote products derived from this software
   15  *    without specific prior written permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  *
   29  *      $KAME: in6_cksum.c,v 1.10 2000/12/03 00:53:59 itojun Exp $
   30  */
   31 
   32 /*-
   33  * Copyright (c) 1988, 1992, 1993
   34  *      The Regents of the University of California.  All rights reserved.
   35  *
   36  * Redistribution and use in source and binary forms, with or without
   37  * modification, are permitted provided that the following conditions
   38  * are met:
   39  * 1. Redistributions of source code must retain the above copyright
   40  *    notice, this list of conditions and the following disclaimer.
   41  * 2. Redistributions in binary form must reproduce the above copyright
   42  *    notice, this list of conditions and the following disclaimer in the
   43  *    documentation and/or other materials provided with the distribution.
   44  * 4. Neither the name of the University nor the names of its contributors
   45  *    may be used to endorse or promote products derived from this software
   46  *    without specific prior written permission.
   47  *
   48  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   49  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   50  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   51  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   52  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   53  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   54  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   55  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   56  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   57  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   58  * SUCH DAMAGE.
   59  *
   60  *      @(#)in_cksum.c  8.1 (Berkeley) 6/10/93
   61  */
   62 
   63 #include <sys/cdefs.h>
   64 __FBSDID("$FreeBSD: releng/8.4/sys/netinet6/in6_cksum.c 174510 2007-12-10 16:03:40Z obrien $");
   65 
   66 #include <sys/param.h>
   67 #include <sys/mbuf.h>
   68 #include <sys/systm.h>
   69 #include <netinet/in.h>
   70 #include <netinet/ip6.h>
   71 #include <netinet6/scope6_var.h>
   72 
   73 /*
   74  * Checksum routine for Internet Protocol family headers (Portable Version).
   75  *
   76  * This routine is very heavily used in the network
   77  * code and should be modified for each CPU to be as fast as possible.
   78  */
   79 
   80 #define ADDCARRY(x)  (x > 65535 ? x -= 65535 : x)
   81 #define REDUCE {l_util.l = sum; sum = l_util.s[0] + l_util.s[1]; ADDCARRY(sum);}
   82 
   83 /*
   84  * m MUST contain a continuous IP6 header.
   85  * off is an offset where TCP/UDP/ICMP6 header starts.
   86  * len is a total length of a transport segment.
   87  * (e.g. TCP header + TCP payload)
   88  */
   89 int
   90 in6_cksum(struct mbuf *m, u_int8_t nxt, u_int32_t off, u_int32_t len)
   91 {
   92         u_int16_t *w;
   93         int sum = 0;
   94         int mlen = 0;
   95         int byte_swapped = 0;
   96         struct ip6_hdr *ip6;
   97         struct in6_addr in6;
   98         union {
   99                 u_int16_t phs[4];
  100                 struct {
  101                         u_int32_t       ph_len;
  102                         u_int8_t        ph_zero[3];
  103                         u_int8_t        ph_nxt;
  104                 } __packed ph;
  105         } uph;
  106         union {
  107                 u_int8_t        c[2];
  108                 u_int16_t       s;
  109         } s_util;
  110         union {
  111                 u_int16_t s[2];
  112                 u_int32_t l;
  113         } l_util;
  114 
  115         /* sanity check */
  116         if (m->m_pkthdr.len < off + len) {
  117                 panic("in6_cksum: mbuf len (%d) < off+len (%d+%d)",
  118                         m->m_pkthdr.len, off, len);
  119         }
  120 
  121         bzero(&uph, sizeof(uph));
  122 
  123         /*
  124          * First create IP6 pseudo header and calculate a summary.
  125          */
  126         ip6 = mtod(m, struct ip6_hdr *);
  127         uph.ph.ph_len = htonl(len);
  128         uph.ph.ph_nxt = nxt;
  129 
  130         /*
  131          * IPv6 source address.
  132          * XXX: we'd like to avoid copying the address, but we can't due to
  133          * the possibly embedded scope zone ID.
  134          */
  135         in6 = ip6->ip6_src;
  136         in6_clearscope(&in6);
  137         w = (u_int16_t *)&in6;
  138         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  139         sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
  140 
  141         /* IPv6 destination address */
  142         in6 = ip6->ip6_dst;
  143         in6_clearscope(&in6);
  144         w = (u_int16_t *)&in6;
  145         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  146         sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
  147 
  148         /* Payload length and upper layer identifier */
  149         sum += uph.phs[0];  sum += uph.phs[1];
  150         sum += uph.phs[2];  sum += uph.phs[3];
  151 
  152         /*
  153          * Secondly calculate a summary of the first mbuf excluding offset.
  154          */
  155         while (off > 0) {
  156                 if (m->m_len <= off)
  157                         off -= m->m_len;
  158                 else
  159                         break;
  160                 m = m->m_next;
  161         }
  162         w = (u_int16_t *)(mtod(m, u_char *) + off);
  163         mlen = m->m_len - off;
  164         if (len < mlen)
  165                 mlen = len;
  166         len -= mlen;
  167         /*
  168          * Force to even boundary.
  169          */
  170         if ((1 & (long) w) && (mlen > 0)) {
  171                 REDUCE;
  172                 sum <<= 8;
  173                 s_util.c[0] = *(u_char *)w;
  174                 w = (u_int16_t *)((char *)w + 1);
  175                 mlen--;
  176                 byte_swapped = 1;
  177         }
  178         /*
  179          * Unroll the loop to make overhead from
  180          * branches &c small.
  181          */
  182         while ((mlen -= 32) >= 0) {
  183                 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  184                 sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
  185                 sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
  186                 sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
  187                 w += 16;
  188         }
  189         mlen += 32;
  190         while ((mlen -= 8) >= 0) {
  191                 sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  192                 w += 4;
  193         }
  194         mlen += 8;
  195         if (mlen == 0 && byte_swapped == 0)
  196                 goto next;
  197         REDUCE;
  198         while ((mlen -= 2) >= 0) {
  199                 sum += *w++;
  200         }
  201         if (byte_swapped) {
  202                 REDUCE;
  203                 sum <<= 8;
  204                 byte_swapped = 0;
  205                 if (mlen == -1) {
  206                         s_util.c[1] = *(char *)w;
  207                         sum += s_util.s;
  208                         mlen = 0;
  209                 } else
  210                         mlen = -1;
  211         } else if (mlen == -1)
  212                 s_util.c[0] = *(char *)w;
  213  next:
  214         m = m->m_next;
  215 
  216         /*
  217          * Lastly calculate a summary of the rest of mbufs.
  218          */
  219 
  220         for (;m && len; m = m->m_next) {
  221                 if (m->m_len == 0)
  222                         continue;
  223                 w = mtod(m, u_int16_t *);
  224                 if (mlen == -1) {
  225                         /*
  226                          * The first byte of this mbuf is the continuation
  227                          * of a word spanning between this mbuf and the
  228                          * last mbuf.
  229                          *
  230                          * s_util.c[0] is already saved when scanning previous
  231                          * mbuf.
  232                          */
  233                         s_util.c[1] = *(char *)w;
  234                         sum += s_util.s;
  235                         w = (u_int16_t *)((char *)w + 1);
  236                         mlen = m->m_len - 1;
  237                         len--;
  238                 } else
  239                         mlen = m->m_len;
  240                 if (len < mlen)
  241                         mlen = len;
  242                 len -= mlen;
  243                 /*
  244                  * Force to even boundary.
  245                  */
  246                 if ((1 & (long) w) && (mlen > 0)) {
  247                         REDUCE;
  248                         sum <<= 8;
  249                         s_util.c[0] = *(u_char *)w;
  250                         w = (u_int16_t *)((char *)w + 1);
  251                         mlen--;
  252                         byte_swapped = 1;
  253                 }
  254                 /*
  255                  * Unroll the loop to make overhead from
  256                  * branches &c small.
  257                  */
  258                 while ((mlen -= 32) >= 0) {
  259                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  260                         sum += w[4]; sum += w[5]; sum += w[6]; sum += w[7];
  261                         sum += w[8]; sum += w[9]; sum += w[10]; sum += w[11];
  262                         sum += w[12]; sum += w[13]; sum += w[14]; sum += w[15];
  263                         w += 16;
  264                 }
  265                 mlen += 32;
  266                 while ((mlen -= 8) >= 0) {
  267                         sum += w[0]; sum += w[1]; sum += w[2]; sum += w[3];
  268                         w += 4;
  269                 }
  270                 mlen += 8;
  271                 if (mlen == 0 && byte_swapped == 0)
  272                         continue;
  273                 REDUCE;
  274                 while ((mlen -= 2) >= 0) {
  275                         sum += *w++;
  276                 }
  277                 if (byte_swapped) {
  278                         REDUCE;
  279                         sum <<= 8;
  280                         byte_swapped = 0;
  281                         if (mlen == -1) {
  282                                 s_util.c[1] = *(char *)w;
  283                                 sum += s_util.s;
  284                                 mlen = 0;
  285                         } else
  286                                 mlen = -1;
  287                 } else if (mlen == -1)
  288                         s_util.c[0] = *(char *)w;
  289         }
  290         if (len)
  291                 panic("in6_cksum: out of data");
  292         if (mlen == -1) {
  293                 /* The last mbuf has odd # of bytes. Follow the
  294                    standard (the odd byte may be shifted left by 8 bits
  295                    or not as determined by endian-ness of the machine) */
  296                 s_util.c[1] = 0;
  297                 sum += s_util.s;
  298         }
  299         REDUCE;
  300         return (~sum & 0xffff);
  301 }
Cache object: 15c15c2c46bfd162fb251cfae46ed2e7
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FreeBSD/Linux Kernel Cross Reference sys/netinet6/in6_cksum.c

FreeBSD/Linux Kernel Cross Reference
sys/netinet6/in6_cksum.c
